Drill bit



Feb, 9, 1943. M. HokANsoN DRILL BIT Filed Oct. 25, 1959 2 Sheets-Sheet 1 Mnmmm l "4' ATTORNEY.

Feb. 9, 1943 M. HOKANSON 2,310,289

DRILL BIT Filed Oct. 225, 1939 2 Sheets-Sheet 2.

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Patented Feb. 9, 19 43 DRILL BIT Martin Hokanson, Duluth, ltfimn, assignor to Eideo, Incorporated, Duluth, Minn, a corporation of Minnesota Application October 23, 1939, Serial No. 300,794

11 Claims.

This invention relates to rotary drill bits and has reference to that type particularly adapted for well drilling or the like.

The principal object is to provide a more durable and efl'icient bit than heretofore known.

Other objects are simplicity of parts, ease of assembly, and interchangeability of worn cutters due to their uniformity of shape and progressive diametrical dimension, also permitting of a larger worn cutter being resharpened and installed in a size smaller cutter compartment.

Still another object is to adapt the basic invention, that is the centripetal action of the rotary cutters, to a type of bit susceptible to the maximum range of modification for ready adaption to different types of work, as it is fully appreciated by those versed in the art that seldom are two holes in well drilling very similar let alone being identical, especially in respect to the character of rock encountered.

Still other objects and advantages of the invention will appear in the following description thereof.

Referring now to the accompanying drawings, forming part of this application, and wherein like reference characters indicate like parts:

Figure 1 is a half central transverse section and elevation of one of the improved bits.

Figure 2 is a. side elevation taken at right angles to Figure 1 with only the terminal cutting elements shown in position therein.

Figures 3 to 10 are modified forms of the disc like cutter elements.

Figure 11 is a side elevation of a modified form of terminal cutter.

Figure 12 is a half front end elevation of the cutter shown in Figure 11.

In the drawings, I represents a relatively short cylindrical shank portion of the bit which terminates upon its upper end in a tapered spigot like portion 2, which may be either screw threaded as illustrated or of a tapered friction like connection common in the art. The opposite terminus of the shank portion I is enlarged materially in one diametrical direction to substantially the full size 01' the hole to be formed by the drill, while in the opposite diametrical direction it is preferably not greater in width than the diameter of the shank portion I, though it is to be understood that the ratio of these dimensions may be varied without departing from the spirit of the invention, but the larger diameter of the drill head is that of substantially the size of hole to be drilled by the bit. and the smaller dimension sufficiently less to permit escape of the bit cuttings upwardly past the drill head, thus resulting in a drill head having multiple alternately spaced cutting elements and longitudinally disposed spaces for the escape of the bit cuttings. I

The extreme outer opposed walls of the head 3 are tapered slightly outwardly in a downward direction so as to provide the necessary clearance, which is customary in drill bits, and from the lower terminal. edges of the tapered head portion the bit is inclined downwardly and inwardly as well as from the two opposite sides of the bit, the latter inclined walls being clearly illustrated at 4 in Figure 2 of the drawings, while the former is of arcuate form in plan view and divided into the arcuately shaped division walls 5 intermediate of which are formed the semi-circular openings or spaces 8 for the reception of the cutting discs 1.

Within the lower inclined face of the head I are shown as installed therein the two inclined cutter carrying shafts, one of which is illustrated at 8, each being journalled axially within the walls 5, the lowermost one of which walls is preferably somewhat thicker than the others to provide additional bearing near the lower end of said shafts, and which portion is illustrated as provided with a plane sleeve bearing, though obviously a ball or roller bearing may be substituted therefor, and the lower terminal of each shaft 8 has fixed thereto, preferably as by being screw-threadedly mounted thereon, the conicallv shaped cutter If. The upper end of each of these shafts has screw-threadedly mounted thereupon the collar I! which is first positioned within the opening I 8 at the outermost extremity of each enlargement of bit head, and into which opening is also installed the suitable thrust bearing indicated at l9.

Upon each shaft 0 are freely rotatably mounted the progressively graduated cutter discs 1, each in its respective opening 8, and preferably carrying axially thereof a suitable ball or roller bearing indicated at H about the shaft so as to result in as free and independent rotary motion of each disc as is possible.

It will be noted that the shafts 8 are preferably disposed at an angle of approximately 45 to the axis of the bit, as this is deemed, for average conditions of drilling, preferable for such a bit, but for special conditions encountered,

either greater or lesser angles will be required. This permits of ea ih cutter 1 being formed of frustro-conical shape, with the cutting edge of each being formed by the intersection of a plane surface and a conical surface at 45 to each other,

This, of course, depends upon the angle of the shaft, for if the shaft angle is less than 45 to the bit axis, the surfaces forming the cuttin edge of the discs would be less than 45 to each other, and vice versa. The outermost or larger one of the cutting discs on each shaft forms the reaming cutter for the hole being drilled, and the conical outermost faces of all discs are disposed parallel with the axis of the bit at the point of cutting, or slightly inclined inwardly. This type of cutting disc and installation within the head and wherein the outermost and largest cutters function to ream the hole, results in the minimum loss of gage during the drilling of the hole. Of course, during the work of drilling, the cutters on each shaft will gradually wear and thus diminish in diameter, but it is obvious that as any of the larger cutters wear to any extent requiring re-sharpening, it may be readily reconditioned and made to function as the next smaller disc, and so on to the smallest of the cutters, which results in the prolongation of the life of the cutting elements of the bit. The two lowermost journal supporting portions of the bit head are formed as diverting extensions from the axial hole in the bit, and which hole provides .means for the conduct of whatever fluid is being employed in the drilling process for the removal of the detritus, and which brings the terminal cutters i3 spaced slightly from each other directly below the entrance to such hole or bore of the bit, which is illustrated at I2. Thus it will be seen that the terminus for the fluid used for removing the detritus is placed a sufllcient distance above the actual cutting face which will prevent the same from being readily clogged up by argillaceous matter and the like while drilling, but at the same time supplying said fluid under pressure to the very bottom of the cutting face, which results in efficient, instantaneous and complete removal of the detritus over the whole cutting face.

The shape and inclination of the cutting discs when assembled as illustrated, or approximately so, results in the most simple and practical manner of accomplishing the paramount feature of such a bit in that each of said cutters are breaking its respective spalls inwardly at all times producing a uniform centripital action of the bit.

The forming of two opposite sides of the head of the bit of the same or approximately the same width as the diameter of the shank l thereof and below which the sides converge as clearly shown in Figure 2 of the drawings, results in ideal freedom for the detritus to escape, and adequately provides against the tendency of clogging of the rotating parts thereof. Inasmuch as this centripetal action of the bit in breaking and crowding the detritus inwardly prevents the collection of same about the marginal wall of the hole being drilled, it is quite apparent that wear on the conical surface of the cutters is reduced to a minimum, which contributes greatly to the advantage of minimum gage loss in the hole being drilled.

Where desired and for special types of drilling, the terminal burrs or cutters may be altered in form somewhat as suggested in Figures 11 and 12, wherein the cutting protrusions on the burr may be both clrcumferentially and diagonally spaced into sharpened elements of any desired form.

In Figures 3 and 4 tions of cutter discs, that shown in Figure 3 beare shown slight modiflcaing what may be referred to as a convex disc or in other words one having a convex inner surface, whereas the form shown in Figure 4 may be referred to as a concave disc, that is having a concaved inner surface.

In Figures 5, 6, 7, 8, 9 and 10 are illustrated modified forms of tooth-like circumferential protrusions which may be resorted to in the construction of the cutting discs for different classes of work.

From the foregoing it is evident that I have produced a type of bit particularly adapted for oil well drilling, which will cut much faster than the conventional bits at present used for this class of work, and furthermore this type of bit will drill a greater distance than the present bits before needing to be resharpened, because of the employment of straight rolling action instead of a combined rolling and twisting action as is the case with the present bits.

While I have shown in the accompanying drawings a bit having five disc like cutting wheels, it is obvious that the number of such wheels used in a certain size of bit may vary with the nature of the rock drilled in, the minimum number of course being one with a cutter wheel in the center.

Infthe drawings there is shown a bit head having two shafts having mounted thereon the cutting wheels ,in diametrically opposite and symmetrical relation, which is, of course, the preferred form, but this might not be essential. Furthermore in larger sized bits it will prove advantageous to have more than two shafts with the cutting wheels thereon, say three, four, five, or even more, the essential feature being that intermediate of each pair of said shafts and cutting wheels there be provided room for the escape of the detritus up past the bit head.

Since the cutting is accomplished by rolling circular cutting wheels around the axis of the bit at the periphery of the hole' drilled or at the periphery and at certain distances from the periphery toward the center of the bit combined with a special rolling cutting bit in the center, it is therefore important that the circle cut by the various wheels be separated from each other by steps, the smaller circle cut always leading over the next larger circle cut, etc.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

1. In a rotary drill of the type describedia head portion having flattened sides and bein downwardly and inwardly inclined, a plurality of spaced openings in said inclined sides, a pinrality of downwardly and inwardly inclined shafts mounted within said head and traversing said openings, a plurality of disc-like cutters carried upon each shaft, each cutter being installed within an opening, and a portion of each cutter extending beyond the lower face of said head, and a central cutter head carried upon the-lowermost end of each of said shafts.

2. In a rotar'y drill of the type described characterized by having a head portion provided with downwardly and inwardly inclined sides, a plurality of spaced openings in said inclined sides, a shaft traversing said openings, a plurality of radially extending series of cutting discs within said head, each disc being installed on a shaft, within an opening and protruding from the lowermost face of said drill, the discs in each series progressively increasing in diameter outwardly from the center of said head. 1

3. In a rotary drill of the type described, a head'portion having a downwardly and inwardly inclined end, a plurality of spaced openings in said inclined end, means for rotatably supporting a plurality of downwardly converging shafts within said head and traversing said openings and symmetrically spaced about the axis thereof, a plurality of disc-like cutters carried upon each shaft, each of said cutters being installed within an opening and having a cutting edge formed by the intersection of a substantially plane surface and' a conical surface the axis of which is coincident with the axis of the disc.

4. In a drill of the type described, a head portion having downwardly converging sides, spaced openings in the converging sides of said head portion, means for rotatably supporting a frustro-conically shaped disc-like cutter in each opening with the conical surfaces of all cutters at the point of cutting being substantially vertical so that the base of each disc breaks the material cut inwardly.

5. In a drill of the type described, a head portion, a plurality of frustro-conically shaped discs rotatably supported within said head portion, all of said discs being positioned within said head that the conical surface thereof at the point of cutting is substantially vertical.

6. In a drill of the type described, a, head portion, means for rotatably supporting a plurality oi downwardly converging shafts within said head symmetrically spaced about the axis thereoi, a plurality of disc-like cutters carried in the same spaced relation upon each shaft, said spaced relation being substantially equal to the width of the disc and the bearing between each pair of rollers, and a central bur-like cutter upon each shaft.

'7. A rotary drill of the type described having at least two groups of a plurality of disc-like frusto-conically shaped cutters and each group mounted upon an inclined shaft extending upwardly and radially from the center of said drill,

characterized by said cutters being spaced apart on their respective shafts a distance sumcient to provide for ample clearance of spalls, and a substantial portion of the bearing for said shaft 5 and each cutter so positioned that the substantially flat cleaving surface of its cutting edge breaks the material inwardly and downwardly into the space formed therebelow.

8. The combination substantially as set forth in claim 7, and a bur-like cutter on the inner lower end of each shaft.

9. In a drill of the type described, a head portion, means for rotatably supporting a plurality of circular disc-like cutters about the axis of said head portion, said cutters progressively informed by said drill.

10. In a drill of the type described, a head portion, a plurality of groups of circular disclike cutters rotatably supported about said head portion, the cutters of each group being spaced and axially aligned in an upward inclined direction from the center to the periphery of the bit so as to form a plurality of upwardly and outwardly stepped circular grooves in the material being drilled, and each cutter being so formed as to break inwardly the ring of material between the groove it cuts and the next smaller groove.

11. A rotary drill of the type described having a plurality of groups of disc-like frustro-conically shaped cutters, an inclined shaft extending upwardly and radially from the center of the drill and supporting each group of cutters, said cutters progressively increasing in size, and each being adapted to cut a circular groove in the material being drilled and break inwardly the material between the groove it cuts and the next smaller groove.

MARTIN HOKANSON. 

